The present invention relates to internal combustion engines, and more particularly, but not exclusively, is relates to operation of an internal combustion engine with a turbocharger.
Turbochargers are well known devices for pressurizing intake air entering the combustion chambers of an internal combustion engine to thereby increase the efficiency and power output of the engine. Generally, pressurizing the intake air increases the quantity of air entering the engine combustion chambers during intake, permitting more fuel to be utilized in establishing a fuel charge with a desired air-to-fuel ratio. Typically, increased engine torque and power results compared to a similar engine that is not turbocharged.
In a turbocharged engine, the exhaust manifold of the engine is in fluid communication with a rotatable turbine of the turbocharger via an exhaust conduit, and the exhaust gas flowing through this conduit causes the turbine to turn at a rate determined by exhaust gas pressure and flow rate. A compressor of the turbocharger is mechanically coupled to the turbine. The compressor is rotatably driven by the turbine as it turns. An inlet of the compressor receives fresh ambient air, and an outlet of the compressor is in fluid communication with an intake manifold of the engine via an intake conduit. The rotation of the compressor increases the amount of intake air supplied to the engine, which results in an increased pressure, often referred to as the “boost” pressure.
An exhaust gas recirculation (EGR) system implemented in such a turbocharged engine supplies controlled amounts of exhaust gas from the exhaust manifold to the intake manifold via an EGR conduit. In order to sustain positive EGR flow through the EGR conduit, pressure in the exhaust conduit is maintained at a level greater than that in the intake conduit, and turbochargers in EGR-based engines typically operate at higher rotational speeds than those without EGR. In either case, it is often desirable to have accurate knowledge of the turbocharger rotational speed—particularly for turbocharged engines with EGR to ensure positive EGR flow while maintaining turbocharger speed within safe operating limits.
In cases where implementation of a turbocharger speed sensor is impractical or cost prohibitive, and/or in cases where redundant or “back-up” turbocharger speed information is desired, what is needed is a system for accurately estimating or synthesizing turbocharger rotational speed. Thus, a demand remains for further contributions in this area of technology.
In one embodiment of the present invention, a unique technique for determining turbocharger speed is provided. In other embodiments, unique methods, systems, and apparatus for determining turbocharger speed are provided.
A further embodiment includes: sensing speed of an internal combustion engine having a turbocharger with a compressor that includes an inlet and an outlet. This outlet is coupled to an intake of the engine. The embodiment further includes sensing inlet pressure and boost pressure of the compressor and determining a value corresponding to turbocharger speed from the speed of the internal combustion engine, the inlet pressure, and the boost pressure. This value is refined as a function of change of the boost pressure with time to represent the turbocharger speed.
Another embodiment comprises: providing an internal combustion engine including a turbocharger with a compressor that has an outlet coupled to an intake of the engine; determining a turbocharger speed estimate from speed of the engine and a pressure ratio for the compressor; and adjusting the turbocharger speed estimate as a function of compressor boost pressure variation with time.
Still another embodiment comprises: an internal combustion engine; a speed sensor operable to provide a first signal representative of engine speed; a turbocharger including a compressor with an inlet and an outlet that is coupled to an intake of the engine; a pressure sensing arrangement operable to provide a second signal representative of intake pressure of the compressor and a third signal representative of outlet pressure of the compressor; and a controller responsive to the first signal, the second signal, and the third signal to determine a value as a function of the engine speed and a pressure ratio. This ratio is taken between the intake pressure and the outlet pressure. The controller is further operable to adjust the value based on variation of the outlet pressure with time to provide a signal representative of turbocharger speed.
Yet another embodiment of the present invention comprises: means for sensing speed of an internal combustion engine that includes a turbocharger. A compressor of the turbocharger includes an inlet and an outlet coupled to an intake of the engine. The embodiment further comprises: means for filtering the speed of the internal combustion engine; means for sensing inlet temperature, inlet pressure, and boost pressure of the turbocharger compressor; means for filtering the boost pressure; means for determining a value corresponding to uncorrected turbocharger speed from the speed of the internal combustion engine, the inlet pressure, and the boost pressure; means for correcting the value with the inlet temperature to correspond to a temperature corrected turbocharger speed; and means for refining the value as a function of change of the boost pressure with time to provide a refined turbocharger speed.
These and further embodiments, forms, features, objects, advantages, benefits, and aspects of the present invention shall become apparent from the detailed description and drawings provided herewith.